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A 12V DC Home Power Lighting System

Did you know that 12v DC CFL lighting can be used as a viable light source in the Home? …or just about anywhere for that matter.

If you are keen on ‘Green Power’, it is possible (for anyone with some fairly basic D.I.Y electrical skills and knowledge) to make and install a 12 volt DC supplemental power system for CFL and ‘new breed’ CCFL (cold cathode) lighting.  A simple 12V DC lighting system can provide a trouble free lighting source for your home and / or other DC powered projects for many, many years. One of the easist ways to tap into some free energy for your 12v lighting is to install Solar Photovoltaic Cells or ‘PV’ cells. It is thought that an average PV panel will last around 20-30 years!  Your ‘PV / 12v lighting system’ can grow and be expanded and added to as and when your funds and / or time allow.

12V DC 3W, 7W CCFL lamps

12V DC 3W, 7W CCFL lamps

Yes, you may be able to install a simple 12 volt power system based on either a wind turbine or solar PV panels (or both). However, you may need to check with your local council authority before proceeding as you may require  planning consent to erect a wind turbine or attach PV panels to your home. Even a fairly small system could cover your regular home lighting requirements completely! This WILL save you real cash on your domestic overheads every year! Sometimes it is possible to attach PV panel(s) to a garden shed or other outbuilding where a good level of sunshine can gain unrestricted access.
Three 12V BP Solar PV Panels regularly produce 16 amps in good sun
Three 12V BP Solar PV Panels regularly produce 16 amps in good strong sun

There are a variety of reasons why a typical residential property owner may want to install a ’small scale’ PV or Wind powered home electrical system… Common reasons are normally a desire to reduce ones electrical bills or to have a back-up system to cover ones home in the event the regular power supply fails.  Other reasons may include a desire to help reduce one’s greenhouse gas emissions and or the impact of energy use on the environment.  Of course, there are many users who install a small scale 12v DC Solar PV system for a remote location such as with farming for use in barns or outbuildings.  New ‘low energy’ 12v CFL and CC CFL (cold cathode) compact fluorescent lamps can provide very powerful lighting for all manner of projects.  This factor is making the viability of small scale PV installations more attractive. Where once, regular 12v automotive (incandescent) lamps would have had to be used (either consuming too much power or giving poor light), new high-tec compact fluorescent and cold cathode lamps can now give the same or better lighting results and economy as equivalent low energy 240v ac cousins.

Use the Sun's Free power to charge your 12v tools and equipment

Use the Sun's Free power to charge your 12v tools and equipment

One can use their solar generated power supply to charge all manner of 12v equipment. Take a look at some of the regular items we use in the image (right). You can also see the 30A BP charge regulator (which is showing a charge rate of 4.2 amps on an average (UK) October afternoon. List includes: 4 mobile phones, 2 powerful professional HID torches (one 10W and one 25W), a quality electric razor, a set of long range 2 way radio’s, charging for 7.5v NiCad packs (radio controlled cars, etc), and charging for a Sony PSP! This one thing will save good money each and every year! No energy wasting  ’Wall Warts’ in use here.

Large outdoor lighting unit with three 12v 5W compact fluorescent lamps

Large outdoor lighting unit with three 12v 3W CCFL compact fluorescent lamps

I can report that even a simple 12v DC system powered either by a small wind turbine or PV panels can provide a very real and useful power source for the home, workshop or virtually any area that requires ‘no strings attached’ power.

We know this because we have used and are still very much using a simple 250W PV system based on 3 BP 85w panels. This brilliant little system has been running without fault or failure for around 4 years and can meet most of our requirement almost year round. Not bad for a rather gloomy (at times) UK.  Circuits in common use include various outdoor security lights (running dusk till dawn, see image of large outdoor triple lamp unit), covering 4 main areas of illumination.  Low wattage CFL 12v fluorescent lamps as well as single chip LED lamps are used. The entire premises are wired using radial circuits, individually protected via suitably rated ‘CB’s. Each circuit terminates with a three pin (round pin) modern switched socket.

Dedicated 'Round Pin' socket for DC use

Dedicated 'Round Pin' socket for DC use

Power at each location is supplied using regular ‘ring main’ twin and earth cabling 2.5mm. Loading not to exceed 8 amps in each case.  These circuits can be used for virtually anything from lighting such as ’standard lamps’, side lamps and table lamps, LCD TV systems, amplification / music systems, for powering / charging a selection of sundry items such as mobile telephone’s, toys, power tools, torches / searchlights, shavers, etc, etc.

This installation uses a 30 amp ‘BP’ solar regulator unit (with comprehensive digital LCD display), a domestic Legrand breaker box / consumer unit fitted with a selection of low amperage breakers (typically 6amp) and an ex salvage battery set totalling 2000Ah (5 banks of 400Ah 2v cells) which is protected by a main service fuse (acquired as salvage from a specialist breakers yard).
The battery set provides a 2000 amp hour power store

5 X 400ah hour Lead Acid Battery sets make a 2000 amp hour power store. Each 12v set consists of six 2v cells.

The system voltage is 12v and is able to distribute power over cable runs exceeding 50ft without appreciable losses using 2.5mm (twin & earth) cable as outlined above. Outdoor cables are of course ‘armour grade’ waterproof / weather proof and the whole system is earthed with it’s own copper ground rod (including the roof mounted PV panels).

During the dullest, darkest months of the year, (Nov to Feb) a 30amp battery charger is used every couple of weeks to supplement the potential shortfall from the PV system. The amount of hours this is employed depends on loadings and available sunlight during this period.

We prefer to utilise the power ‘as it comes’ to power an amazing array of 12V DC equipment and lighting. This avoids the extra losses (and cost) associated with using an inverter to create 240V AC power.  Of course many users prefer to operate an inverter and this is of course, always an option. However, serious consideration must be given to how the 240V AC power will be safely used and distributed around the property.
I have to stress that one must be confident in and have some knowledge of basic electrical circuits before deciding to undertake such a project.  Any 12DC installation using Lead acid batteries must be undertaken carefully to ensure safety at every stage.
It is important not to overload any circuit / switch employed. When adapting regular domestic AC switch gear, etc, it is important to note that no guide lines are supplied regarding  recommended DC current loadings when using equipment normally associated with AC circuits. A 12V DC device rated at 100w will present a load 20 times higher than the equivalent AC 100w circuit. E.g: 100w @ 12V DC = 8.3 amps whereas 100w @ 240v AC will equal just 0.42 amps.

10200cc Radial Engine Powering A Goggomobil

How could a 10.2 litre aero engine possibly fit into a tiny little car? Well it’s true, just take a look at the video below to see just how this was achieved.

Not the greenest of projects by an absolute mile but you have to give this fellow 10/10 for truly amazing accomplishment - I would love to have him on my team!

I am happy to report that installing a simple little supplementary 12V wind or solar PV powered 12V DC lighting system in your home, workshop or outbuildings is a whole lot easier and with very much fewer ingredients.

Pilot Whale Massacre - Faroe Islands

I am always very keen to learn and hopefully understand more about the animals we co-habit our planet with. I an no expert when it comes to matters concerning the culling, capture, murder or otherwise mutilation of wild animals and often find even necessary culling of overpopulated or dangerous animals distasteful.  I recently became aware of something that I find deeply disturbing and to be honest, I am having trouble understanding…
If anyone can explain why the slaughter of Pilot whales is actually necessary, I will be keen to attempt to learn. PLEASE DO NOT VIEW the short video below OR the pictures unless you have a strong stomach. It is not my intention publish freakish or unpalatable news items here on the OnSolar blog, please accept my apologies if it is upsetting but I find this lunacy breathtakingly pitiful – it should be stopped.
Like many dolphins and their relatives, the ’Pilot Whale’ (I believe this to be the correct name for these particular animals) has an inquisitive, friendly nature and seems easily duped – not initially afraid of people… Feel free to comment.
I have amended the above information today (20/11/09) as is it was not correct in fact. I have been suitably updated and can inform anyone reading this post that the ‘Dolphins’ are actually whales, Pilot Whales. Much of the information currently in circulation around the ‘web’ regarding this bizarre slaughter is not accurate due to some errors in translation from the original article (which I have to say, I strongly suspected). Many thanks to PhilBee in New Zealand for taking the time to help clarify. You can gain a little more info here.

Below is a short sequence of pictures which illustrates the methods used to dispatch these creatures…

Calderon-Dolphin-Massacre-Denmark

Calderon-Dolphin-Massacre-Denmark-7

Calderon-Dolphin-Massacre-Denmark-4

Calderon-Dolphin-Massacre-Denmark-2

Calderon-Dolphin-Massacre-Denmark-11

Calderon-Dolphin-Massacre-Denmark-8

Calderon-Dolphin-Massacre-Denmark-6

The York Astronomical Society 12V DC Lighting System

Your Astronomical Society kindly prepared the following article to tell us a little about their 12V DC solar PV powered lighting system.

P Buglass says: Since we officially opened the YAS Observatory at our “secret location”, we had plans to provide electric lighting, both white and red.  The provision of suitable lighting was made more awkward by the fact that there is no mains electricity available at our site, therefore any power we use would have to be either brought with us, or generated at the site…

Our previous observatory took the first approach and we used a 12V car battery which had to be periodically taken away to be recharged.  This was far from ideal and we never knew quite when the battery would run out leaving us in the dark, literally.

For the new observatory we decided on a different approach and settled on a design which incorporated a solar voltaic panel and a number of deep cycle 12V batteries.  The power system was installed last Summer and has been tweaked over the Winter and is now able to provide all the lighting needs of the observatory.

The set-up consists of a 43W solar panel which uses a 4 Amp charge controller to change a pair of 12V 115AHr deep cycle batteries, wired in parallel to provide 230AHr of capacity.  A more expensive mono-crystalline solar panel was selected due to its smaller size/power ratio as it had to fit inside our cabin windows. 

View of panel as seen from the inside

View of the 43w PV panel as seen from the inside

 

Two 12v 110Ah Lead Acid 'Gel' batteries in parallel complete the battery store

Two 12v 110Ah Lead Acid 'Gel' batteries in parallel complete the battery store

The regulator ensures a stable charge rate to the battery set

The regulator ensures a stable charge rate to the battery set

Our original plan was to mount the solar panel on the roof of our portacabin, but we were concerned about security and didn’t want to make it too visible.  Some maths was performed to look at the angle of the Sun in Winter and Summer, and we decided to mount our panel vertically in one of the cabin’s south facing windows.  The maths showed that in Winter when the Sun was low, we would actually generate more power than if the panel had been roof mounted at 18 degrees (an angle we had decided was the maximum we could use and still keep the panel invisible).  Therefore we decided to go for window mounting to maximise our Winter power, (the time of year we need it the most).  In Summer time, the Sun is much higher, and therefore the vertical panel is much less efficient, but the overall power generated due to the longer days makes up for this.

Under bright sunlight the panel can put almost 3Ahr into the battery bank, but a realistic figure is closer to 2Ahr in Winter time.  Even with a conservative estimate of only 1 hour per day of bright sunlight during the winter months, we can still expect to put over 12Ahr into the batteries during the week, which will allow us to use our lights for 6 to 8 hours at a weekend without depleting the batteries on a week by week basis.  In Spring and Autumn the figures are more like 30Ahr a week into the batteries, which is more than enough for a few nights of observing at the weekends.  In the Summer time we will have power to spare so we will be holding lots of summer BBQs and other evening activities . . . . Bingo anyone?

As with any 12V power system, protective fuses and thick cables are essential.  Power loss in a cable is proportional to the square of the current, so with a low voltage system more current is required for a given power, thus increasing the wiring losses significantly.  Power loss = I2R, where I is the current drawn, and R the resistance of the wires, so reducing wiring resistance by using thick cables reduces power loss.  We used the thickest mains cable we could lay our hands on, and it seems to work well with minimal power loss indicated by the voltage level hardly dropping under load.  Where we have a long cable run down the inside of our 40 ft steel shipping container observatory area, we have used a double run of thick twin and earth cable, with all the separate conductors, wired together giving one cable for positive and the other for negative.  This may be overkill, but we can pull quite a few Amps through this wiring arrangement with minimal voltage drop at the far end.

The power feed out of the batteries is protected by a 30A in-line fuse (car spade type for easy replacement), and this will likely be up-rated to 40A, or more, in the future as additional power hungry equipment is installed in the observatory such as a mains AC voltage inverter to power laptops, etc. 

The white lights we use are low energy, compact fluorescents, rated at 7W and 11W, and take less than 1A from our system, but they are unique in that they are designed to operate directly off a 12V DC supply, so they contain an integrated 12V inverter to power them.  They look just like other low energy light bulbs you would find in your house, and give a similar light level you would expect from your bulbs at home.  The use of ES (screw) fittings is desirable, as these are easier to ensure the correct polarity is maintained, however the bulbs can be bought in either ES or Bayonet fittings.

Low energy 12V CFL lighting

Low energy 12V CFL lighting

The warm room cabin has been provided with a single 11W bulb, with a switch beside the cabin door, which provides adequate light for most activities such as reading, committee meetings, etc.  A 7W bulb has been installed in a bulkhead fitting on the observing deck for setting up and clearing away purposes, again with it’s own adjacent switch.  Finally there is another 11W bulb and switch above the main door into the container, but again the use of this light will be limited to setting up and clearing away, as both this light and the observing deck light will normally be turned off during observing, when red lights will be used exclusively.

The red light in the observatory is provided by a number of small 12V festoon lights, which contain 8 red LEDS each.  One red light is located next to the container door with a master red light switch, and two more red lights illuminate the stairs up to the observing deck.  On the observing deck itself there are 2 additional red lights, but these can be switched on and off independently of the other red lights if needed, i.e. if CCD imaging was being undertaken and all lighting on the observing deck needed to be extinguished.

Now that the observatory lighting is fully operational, we are working on installing a table area for laptop PCs in the cabin, which will have a small mains power inverter, running off our 12V supply.  This will enable observers to use and recharge their laptops as needed.  We will also be able to tap off  12V feeds to the telescope pillar, and the 12” other Newtonian telescope drive system, in the latter case again utilising a small mains inverter.

If the additional power demands of the laptop station and telescope drives prove to be taking more out of the batteries than we can put back during the week, we have the option of installing a second 43W solar panel in another south facing window, thus doubling our power generation capacity.

It has been a very rewarding exercise to equip the YAS observatory with a “renewable” energy lighting and power system, and it has demonstrated that something similar could be done on a domestic scale to provide limited household lighting and power too.  Holding committee meetings in the observatory with a bright light available at the flick of a switch, without having to fire up the petrol generator, is a great convenience, and one which shouldn’t be underestimated.

The costs of the major system components were £249 for the solar panel, about £50 for each battery, and approximately £10 per 12V low energy bulb.  The wiring and other ancillary switches, etc, have come mainly from our “bits and bobs” boxes.  Thanks should go out to all those who have helped me put the power system together and get it wired up and working.

I feel it is very appropriate and fitting, for us to be utilising power derived directly from our nearest star, the Sun, to help us in our night time observations of other stars and celestial objects.  Long live “Star Power”!

P Buglass, York Astronomical Society,  April 2009. http://www.yorkastro.org.uk/

We would like to say Thank You to P Buglass for telling us about his solar PV project and hope that he continues to enjoy the benefits of the ‘Off Grid’ 12v solar PV power system. Long may your 12v cfl lamps perform! Ken. OnSolar.co.uk 

Keeping A Healthy 12v Battery Pack!

In our experience, one of the quickest ways to destroy a lead acid battery set is to regularly discharge it to a low voltage. We would not advise running a battery below around 75% capacity or below around 12.3v as it’s life will be dramatically shortened.
Battery condition / state of charge chart

Battery condition / state of charge chart

Another area which must be regularly checked is the external condition of the battery top(s) including vent plugs, caps, terminals and connecting cables.  After several months in service, a Lead Acid battery can produce a fine ‘mist like’ corrosive film on itself including it’s terminals and cable connectors. left unchecked this will result in problems including a higher rate of self discharge and eventually corrosion. Just one year of poor maintenance can put a battery into an early decline and see your project failing prematurely.
A battery can be cleaned quite easily using a prepared mix of water soapy water to wash away the layer of acid encrusted dust (the layer of mist). Acid spillages or more prominent areas of ’sweating’ or damp should be removed using a strong solution of baking soda in water, finally rinsing with clean water. Care must be taken to avoid any cleaning substance entering the battery, vent plug or any automatic battery top up devices. After cleaning, a nice smear of petroleum jelly can be liberally applied to any metal parts and contact areas. Ensure that all connections are tight, corrosion and rust free. Cables with any visible damage, burns or missing insulation should be repaired or replaced to prevent future problems.